Vacuum casting apparatus



Feb. 6, 1962 H. c. BIGGE VACUUM CASTING APPARATUS 5 Sheets-Sheet 1 Filed Oct. 27. 1958 lllllllllllllll lllllllllillll INVENTOI Henry C. B/yye Feb. 6, 1962 H. c. BIGGE VACUUM CASTING APPARATUS 3 Sheets-Sheet 2 Filed Oct. 27, 1958 INVENTOR Henry C. B/Iyye BY WW ATTORNEY Feb 6, 1962 H. c. BlGGE VACUUM CASTING APPARATUS Filed Oct. 27, 1958 3 Sheets-Sheet 3 INVENTOR Hen/"y C 5/996 ATTORNEY United States atent O 3,019,496 VACUUM CASTING APPARATUS Henry C. Bigge, Bethlehem, Pa., assignor to Bethlehem Steel Company, a corporation of Pennsylvania Filed Oct. 27, 1958, Ser. No. 769,624 11 Claims. (Cl. 2273) This invention relates to a vacuum degassing apparatus for molten metals. It relates particularly to apparatus used to control molten metal flowing into the vacuum chamber.

Several different types of units have been used to degasify molten metal. One type of degassing unit similar to my unit is shown by De Mare in US. Patent No. 2,- 253,421. Molten metal is transferred from a large furnace ladle into a smaller pony ladle that is fastened to the top of an evacuated tank. The molten metal then flows from the small pony ladle into another ladle or an ingot mold placed inside the evacuated tank. When the molten metal flows into the evacuated tank the vacuum tears the metal stream into a spray of small droplets. The spray effect is essential for degasification of the metal since the metal droplets then have a large surface area exposed to the degasification action of the vacuum.

At the high vacuums necessary for effective degasification the spray assumes such a wide angle conical shape during the drop into the ingot mold or ladle that frequently the metal droplets fall outside the ingot mold and solidify on the inside of the vacuum tank or on the outside of the ingot mold. The solidified metal must then be chipped off the ingot mold and the tank before this apparatus can be used again. The spraying of molten metal droplets on the walls and top of the vacuum tank may also create unequal thermal stresses great enough to cause cracks in the vacuum tank.

The conical shape of the spray tends to build up a cone of solidified metal around the orifice where the molten metal flows into the vacuum tank. In pouring a large ingot the cone may reach a diameter of two feet and weigh several hundred pounds. Experience has shown that often when the tank cover was removed at the conclusion of pouring, the cone would break off and drop into the still molten ingot below. An ingot with an inclusion like this could not be used except for scrap.

It is therefore an object of my invention to provide apparatus that will retain the solidified cone formed at the pouring orifice.

Another object of my invention is to provide apparatus that will aid the formation of a cone around the pouring orifice.

It is a further object of my invention to provideapparatus for guiding the metal spray in such a manner that the metal droplets will all fall inside the ingot mold placed inside the vacuum chamber.

The foregoing objects and the means whereby they are attained will be more fully understood from the following description and claims together with the drawings in which FIGURE 1 is a schematic diagram of the apparatus used to degasify the molten metal as it flows into an ingot mold.

FIGURE 2 is a cross-section showing the pouring funnel assembly.

FIGURE 3 is a bottom View showing the placement of the cone retaining members.

FIGURE 4 is a cross-section showing a modification of my invention.

FIGURE 1 shows a vacuum degassing unit Where 1 is the furnace ladle, the one into which the metal was tapped from the furnace. Directly under ladle 1, and seated on the vacuum tank dome 4 is a smaller pony ladle 2. There is a vacuum-tight gasket seal 3 between ladle 2 and the vacuum tank dome 4. Stopper rods 5 control the flow of metal out of the ladies 1 and 2. The nozzle 6 of ladle 2 is directly over an aluminum rupture disc 7, this seal obviously being necessary in order to obtain the vacuum in the tank prior to pouring. The vacuum chamber proper consists of two steel sections, a stationary straight sided bottom portion 8, and a removable cover or dome 4. A gasket ring 9 is used to provide a vacuum seal between the dome 4 and the stationary section of tank 8. The ingot mold 10 rests upon a stool 11 and a sinkhead 12 is placed on top of the ingot mold 10. Instead of an ingot mold, another ladle could be placed in the vacuum chamber to hold the molten metal after it has been degassed. Viewing ports 13 are placed to permit the operator to view the pouring operation and the level of the metal in the mold. These ports 13 may also be equipped with movie or television cameras. Vacuum line 14 leads from the vacuum chamber to a battery of vacuum pumps.

The pouring funnel assembly 15 will be: more fully understood by referring to FIGURE 2. A ceramic nozzle 6 is placed in the bottom of ladle 2. Nozzle 6 is held in place by a steel ring 16 bolted to the bottom of ladle 2. Another steel ring 17 fastens the spherical aluminum rupture disc 7 to steel ring 16. Directly under the rupture disc 7 is a round refractory funnel 18, whose opening 19 tapers downward. The refractory funnel 18 is placed inside a flanged steel retaining cylinder 20, the flange of which is bolted to the vacuum tank dome 4. The steel cylinder 20 may also be bolted to a separate lower steel retaining cylinder 21 to permit easy replacement of the refractory funnel 18 after each pouring. A circular retaining ring 22 that holds the refractory funnel 18 in place is bolted to the retaining cylinder 21. A plurality of depending rods or headed members 23 are fastened to the under surface of the retaining ring 22 and encircle the lower orifice 24 of the refractory funnel 18.

The funnel 18 controls and guides the molten metal flow as it breaks up into droplets under the action of the vacuum.

The length and orifice diameters of the funnel 18 and the distance of the lower orifice 24 above the sinkhead 12 will vary according to the size of ingot being poured and the pouring rate. The high vacuum will start to break up the metal stream as it flows through the funnel but the tapered funnel confines and directs the stream so that the conical spray formed is uniform and all the droplets fall inside the ingot mold.

The depending members 23 become imbedded as the cone 25 of solidified metal builds up around the orifice 24 of the funnel 118 as shown in dotted lines in FIG. 1. When the dome 4 is removed at the conclusion of the pour the firmly imbedded members 23 hold the cone and prevent it from dropping off into the ingot mold below. I prefer to use four rod shaped members 23, as I find this number to be sufiicient to hold the cone. However, any number of rods or similar shaped depending members, such as a headed member may be employed. Also, instead of rod like members other types of depending means for supporting a cone could be employed, such as an open wire frame, wire mesh, sheet metal frame or the like. It is within the scope of my invention that since a metal mass would build up around any orifice where a molten metal flow enters a vacuum chamber, the depending members could be used without the pouring funnel. This modification is shown by FIGURE 4 in which the members 23 are secured to and depend from the underside of the vacuum chamber cover 4 and encircle the molten metal inlet in cover 4.

A specific embodiment of my invention used a funnel long with its lower orifice 11" above the top of a 54" diameter sinkhead. Four 1 /4 diameter rods 3" long firmly held a 21" diameter cone weighing 150 pounds.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. Apparatus for guiding molten metal into a vacuum chamber, said apparatus comprising a refractory funnel set into a metal retaining cylinder, said retaining cylinder being fastened to the top of said vacuum chamber and extending down into said vacuum chamber, a retaining ring attached to said retaining cylinder and supporting said refractory funnel, and a plurality of depending metallic members fastened to said retaining ring, whereby to retain a cone of solidified metal formed during pouring of said molten metal into said vacuum chamber.

2. Apparatus for guiding molten metal into a vacuum chamber, said apparatus comprising a refractory funnel set into a metal retaining cylinder, said retaining cylinder being fastened to the top of said vacuum chamber and extending down into said vacuum chamber, a retaining ring attached to said retaining cylinder and supporting said refractory funnel, and a plurality of elongated depending members fastened to said retaining ring, whereby to retain a cone of solidified metal formed during pouring of said molten metal into said vacuum chamber.

3. Apparatus for guiding molten metal into a vacuum chamber, said apparatus comprising a refractory funnel set into a metal retaining cylinder, said retaining cylinder being fastened to the top of said vacuum chamber and extending down into said vacuum chamber, a retaining ring attached to said retaining cylinder and supporting said refractory funnel, and a plurality of elongated rod shaped depending members attached to said retaining ring, whereby to retain a cone of solidified metal formed during pouring of said molten metal into said vacuum chamber.

4. Apparatus for guiding molten metal into a vacuum chamber, said apparatus comprising a refractory funnel set into a metal retaining cylinder, said retaining cylinder being fastened to the top of said vacuum chamber and extending down into said vacuum chamber, a retaining ring attached to said retaining cylinder and supporting said refractory funnel, and a plurality of elongated headed depending members attached to said retaining ring, whereby to retain a cone of solidified metal formed during pouring of said molten metal into said vacuum chamber.

5. Apparatus for retaining a metallic cone formed in a vacuum chamber, said apparatus comprising a plurality of members secured to and depending from the top of said vacuum chamber and encircling a molten metal inlet in thetop of said vacuum chamber, whereby to retain a cone of solidified metal formed during the pouring 'of said molten metal into said vacuum chamber.

6. Apparatus for retaining a metallic cone formed in a vacuum chamber, said aparatus comprising a plurality of elongated members secured to and depending from the top of said vacuum chamber and encircling a molten metal inlet in the top of said vacuum chamber, where-by to retain a cone of solidified metal formed during the pouring of said molten metal into said vacuum chamber.

7. Apparatus for retaining a metallic cone formed in a vacuum chamber, said apparatus comprising a plurality of elongated rod shaped members secured to and depending from the top of said vacuum chamber and encircling a molten metal inlet in the top of said vacuum chamber, whereby to retain a cone of solidified metal formed during the pouring of said molten metal into said vacuum chamber.

8. Apparatus for retaining a metallic cone formed in a vacuum chamber, said apparatus comprising a plurality of elongated headed members secured to and depending from the top of said vacuum chamber and encircling a molten metal inlet in the top of said vacuum chamber, whereby to retain a cone of solidified metal formed during the pouring of said molten metal into said vacuum chamber.

9. Apparatus for guiding molten metal into a vacuum chamber comprising a funnel mounted at the top of and extending downwardly into said vacuum chamber, and a plurality of depending metallic members secured to the bottom of said funnel, whereby to retain a cone of solidified metal formed during pouring of said molten metal into said vacuum chamber.

10. Apparatus for guiding molten metal into a vacuum chamber comprising a funnel mounted at the top of and extending downwardly into said vacuum chamber, and a plurality of elongated downwardly directed members mounted circumferentially of the bottom of said funnel, whereby to retain a cone of solidified metal formed during pouring of said molten metal into said vacuum chamber.

11. In apparatus for casting molten metal into a vacuum, a vacuum chamber, means located within said chamber to receive molten metal, a molten metal inlet in the cover of said chamber for pouring molten metal into said chamber, and depending means secured to the underside of said cover and located circumferentially of' said molten metal inlet to retain a body of solidified metal which is formed during pouring of said molten metal.

References Cited in the file of this patent UNITED STATES PATENTS 917,257 Critchlow Apr. 6, 1909. 1,298,036 Gathmann Mar. 25, 1919 1,323,583 Earnshaw Dec. 2, 1919 1,417,269 MacMichael May 23, 1922 2,087,824 Tully July 20, 1937 2,734,241 Southern Feb. 14, 1956 FOREIGN PATENTS 22,594 Great Britain Oct. 17, 1902 866,231 Germany Feb. 9, 1953 

